Purists may shudder at the idea of altering the sea in any way. But Mr. Taylor, who uses marine-grade concrete specially prepared to entice coral and be close to neutral pH, notes that the exhibit inhabits but a fraction of the sea.

“It’s like putting a sculpture in the Sahara,” he said, contending that the works contribute to the greater good of preserving the natural reef by diverting divers away from it.